Through December 25, they will become even cozier. Look for the Jupiter-Saturn conjunction low in the western sky for about an hour after sunset each evening during this time.

While these two planets may appear close, they are still hundreds of millions of miles apart, according to NASA. Hope for clear skies because the conjunction will be visible around the world, with the best perspective for those near the equator.

Unusual molecule found in atmosphere on Saturn's moon Titan. The planets will be bright enough to be viewed in twilight, which may be the best time for many US viewers to observe the conjunction.

If you're in New York or London, or along those latitudes, try to spot the conjunction right after sunset. The second is that measurable, predictable astronomical events occur with relative frequency.

The quest to discover which event, if any, Matthew might have had in mind is therefore a complicated one.

The theory that the conjunction of Jupiter and Saturn may be the Star of Bethlehem is not new. It was proposed in the early 17th century by Johannes Kepler , a German astronomer and mathematician.

Kepler was not the first to suggest that the Star of Bethlehem may have been a recognizable astronomical event.

Four hundred years prior to Kepler, between and , the Italian artist Giotto painted the star as a comet on the walls of the Scrovegni Chapel in Padua, Italy.

The last time that the two planets were easily observable when separated by less than 0. This was the closest together that Jupiter and Saturn have been since —which was nine years before Galileo published a controversial book to promote the idea that the Earth moves around the Sun.

The solar system is the shape of a thin disk: the Earth, the Moon, and the planets orbit the Sun in roughly the same plane.

Astronomers call this plane the ecliptic. Because of this alignment, the Sun, the Moon, and the five planets visible to the naked eye—Mercury, Venus, Mars, Jupiter, and Saturn—follow the same general path as they travel across the Earth's sky.

This is why the Sun, the Moon, and the planets sometimes meet in the sky. These meetings are conjunctions. Conjunctions involving the Moon happen frequently.

As it circles the Earth once a month , the Moon passes each of the planets in the sky. When the Moon passes the Sun, the result can be an eclipse which is where the term ecliptic comes from.

The reason an eclipse doesn't happen every month is that the Moon's orbit is slightly tilted in relation to the ecliptic, and it normally passes above or below the Sun.

How often do solar eclipses occur? A conjunction of Jupiter and Saturn, on the other hand, is relatively rare: it only happens about once every 20 years.

Avoid tall buildings or mountains, and look toward the low southwestern horizon right after sunset. If you're too early, you might miss a fainter Saturn.

The best viewing conditions will be near the equator. There will be less time to catch a glimpse farther north. There's no better way to celebrate the longest night of the year than watching the stars.

So if you're planning a night of stargazing on the solstice, start off by admiring the largest planets before they set. If you miss this conjunction and want to see the planets with the same proximity, just higher in the sky, it won't happen until March 15, -- and then not again until after Between 0 and CE, or Common Era, only seven conjunctions were or will be closer than this one -- and two of those were too close to the sun to be seen without a telescope, according to Hartigan.

So, yes, this is an incredibly rare event. In case weather conditions in your area aren't agreeable to witnessing this celestial event, several livestreams will be available.

The Lowell Observatory in Flagstaff, Arizona, will host a program beginning at 7 p. Hide Caption. Astronomy: Jupiter and Saturn will meet in this rare cosmic conjunction.

Jupiter and Saturn will appear their closest since the days of Galileo in this rare space event. Share your feedback to help improve our site!